The Other Prelude
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(Difference between revisions)
Uchchwhash (Talk  contribs) (String class?) 
Uchchwhash (Talk  contribs) (ifthenelse and Utilities) 

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Although, not Haskell 98, hierarchical modules will definitely be in Haskell'. We take it for granted. 
Although, not Haskell 98, hierarchical modules will definitely be in Haskell'. We take it for granted. 

* <hask>TheOtherPrelude</hask>  Minimalistic module. 
* <hask>TheOtherPrelude</hask>  Minimalistic module. 

−  * <hask>TheOtherPrelude.Extension</hask>  Convenient definitions. 
+  * <hask>TheOtherPrelude.Utilities</hask>  Convenient definitions. The reasoning behind its existence is that we want the Prelude to be very concise. It should not steal good names. 
== Open Issues == 
== Open Issues == 

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The imaginery Prelude as it stands, 
The imaginery Prelude as it stands, 

−  +  === <hask>TheOtherPrelude</hask> === 

<haskell> 
<haskell> 

+   module: TheOtherPrelude 

import Prelude ()  hide everything 
import Prelude ()  hide everything 

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</haskell> 
</haskell> 

+  === <hask>TheOtherPrelude.Utilities</hask> === 

+  <haskell> 

+   module: TheOtherPrelude.Utilities 

+  
+  import Prelude ()  hide everything 

+  
+   this is the ifthenelse proposal 

+   the name has been chosen to reflect the magic of Church booleans! 

+  boolean True x _ = x 

+  boolean False _ y = x 

+  
+  </haskell> 

== How To Use == 
== How To Use == 

<haskell> 
<haskell> 

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* [[Prelude extensions]] and [[Prelude function suggestions]]  Unlike ''The Other Prelude'' they ''enhance'' the Prelude. 
* [[Prelude extensions]] and [[Prelude function suggestions]]  Unlike ''The Other Prelude'' they ''enhance'' the Prelude. 

* [[Functor hierarchy proposal]]  Making <hask>Monad m</hask> imply <hask>Functor m</hask> (adopted by ''The Other Prelude''). 
* [[Functor hierarchy proposal]]  Making <hask>Monad m</hask> imply <hask>Functor m</hask> (adopted by ''The Other Prelude''). 

−  * [[Ifthenelse]]  Making <hask>if</hask> a function. 
+  * [[Ifthenelse]]  Making <hask>if</hask> a function (partially adopted by ''The Other Prelude'', we are silent on the bigger issue of sugar). 
* [http://software.complete.org/missingh/static/doc/ MissingH]  Functions "missing" from the Haskell Prelude/libraries. 
* [http://software.complete.org/missingh/static/doc/ MissingH]  Functions "missing" from the Haskell Prelude/libraries. 

* [[MonadPlus reform proposal]]  Clarifies ambiguities around MonadPlus laws (adopted by ''The Other Prelude'') 
* [[MonadPlus reform proposal]]  Clarifies ambiguities around MonadPlus laws (adopted by ''The Other Prelude'') 
Revision as of 06:15, 30 December 2006
Contents 
1 Call For Contribution
This fun project, called The Other Prelude, is a creative reconstruction of the standard Prelude. By disregarding history and compatibility, we get a clean sheet.
2 Committee
This project has no committee whatsoever. Haskell community discussed the issues here.
3 Naming Conventions
 Function names should be easy for beginners to consume.
 Specifically, The Other Prelude naming convention is to use
 descriptive symbols for functions that are naturally infix (e.g., is replaced bymplus)(++)
 whole English words and camelCase for functions (e.g., but notorElse)fmap
 descriptive symbols for functions that are naturally infix (e.g.,
4 The Hierarchy
Although, not Haskell 98, hierarchical modules will definitely be in Haskell'. We take it for granted.
  Minimalistic module.TheOtherPrelude
  Convenient definitions. The reasoning behind its existence is that we want the Prelude to be very concise. It should not steal good names.TheOtherPrelude.Utilities
5 Open Issues
 Should Prelude functions use instead ofInteger?Int
 Should be a class rather than a type synonym?String
6 The Code
Currently, the code is in Wiki form. If people do agree that the collaborative decisions begot something pretty, we'll have a group of files in darcs.haskell.org some time.
The imaginery Prelude as it stands,
6.1 TheOtherPrelude
TheOtherPrelude
 module: TheOtherPrelude import Prelude ()  hide everything  the idea is to remove 'fmap'.  both map :: (a > b) > [a] > [b] ('fmap' for the monad [])  and (.) :: (a > b) > (e > a) > (e > b) ('fmap' for the (>) e monad)  are good names, and are intuitively prefix and infix respectively. class Functor f where  'fmap' is guilty of nothing but a bad name map, (.) :: (a > b) > f a > f b  implementing either is enough map = (.) (.) = map  the following has been shamelessly copied,  from the [[Functor hierarchy proposal]] wiki page. class Functor f => Applicative f where  lifting a value return :: a > f a  should this be named 'ap'? is 'ap' a good name?  can you come up with a better name?  can it refactor the liftM* type gymnastics? (<*>) :: f (a > b) > f a > f b  this leaves little left for the actual Monad class class (Applicative m) => Monad m where  the binding operation, gist of a monad (>>=) :: m a > (a > m b) > m b  throwing out the outer monad join :: m (m a) > m a  when the second is independent of the first  included in the class in case performance can be enhanced (>>) :: m a > m b > m b  intuitive definitions fa >> fb = (map (const id) fa) <*> fb  is there a better definition? x >>= f = join (map f x) join x = x >>= id  we shamelessly copy from the [[MonadPlus reform proposal]] now.  zero will be used when pattern matching against refutable patterns in  donotation as well as to provide support for monad comprehensions.  should satisfy 'left zero': zero >>= f = zero class (Monad m) => MonadZero m where zero :: m a  should satisfy 'monoid'  zero ++ b = b, b ++ zero = b, (a ++ b) ++ c = a ++ (b ++ c)  and 'left distribution'  (a ++ b) >>= f = (a >>= f) ++ (b >>= f) class (MonadZero m) => MonadPlus m where (++) :: m a > m a > m a  should satisfy 'monoid'  zero `orElse` b = b, b `orElse` zero = b  (a `orElse` b) `orElse` c = a `orElse` (b `orElse` c)  and 'left catch'  (return a) `orElse` b = a class (MonadZero m) => MonadOr m where orElse :: m a > m a > m a
6.2 TheOtherPrelude.Utilities
TheOtherPrelude.Utilities
 module: TheOtherPrelude.Utilities import Prelude ()  hide everything  this is the ifthenelse proposal  the name has been chosen to reflect the magic of Church booleans! boolean True x _ = x boolean False _ y = x
7 How To Use
 ''The Other Prelude'' is an alternative, not a replacement.  So we need to hide everything from the Prelude import Prelude ()  This is just an example assuming there is nothing to hide import TheOtherPrelude  Hopefully, this module will contain lift,...  Standard convention is to use M.lift (instead of liftM) import qualified TheOtherPrelude.Monad.Kleisli as M
8 See also
 Mathematical prelude discussion  A numeric Prelude in good shape already. Will a merger be ever possible?
 Prelude extensions and Prelude function suggestions  Unlike The Other Prelude they enhance the Prelude.
 Functor hierarchy proposal  Making implyMonad m(adopted by The Other Prelude).Functor m
 Ifthenelse  Making a function (partially adopted by The Other Prelude, we are silent on the bigger issue of sugar).if
 MissingH  Functions "missing" from the Haskell Prelude/libraries.
 MonadPlus reform proposal  Clarifies ambiguities around MonadPlus laws (adopted by The Other Prelude)